A Boolean expression is a logical statement that is either true or false. Boolean expressions can compare data of any type as long as both parts of the expression have the same basic data type. Boolean expressions allow for the testing of data to see if it is equal to, greater than, or less than other data.
A Boolean expression includes Boolean data, such as Boolean values (YES and NO, and their synonyms, ON and OFF, and TRUE and FALSE), Boolean variables or formulas, functions that yield Boolean results and Boolean values calculated by comparison operators. For example, with the Boolean expression shown below, each value of the variable “actual” is compared to the constant 20,000. If the value is greater than 20,000, then the statement is true; if the value is less than or equal to 20,000, then the statement is false.
Actual GT 20000
There are many applications that use and compare Boolean expressions of features to find matching attributes. For example, online content publishing applications may select lists of advertisements that match a user visit profile associated with a web page for display with content requested by a user. Similarly, electronic commerce (“ecommerce”) applications may select a list of products that match the attributes of product information requested by a user and may also select a list of advertisements that match the attributes of product information requested by a user. Further, online search advertising applications may select a list of advertisements that match the user visit profile associated with a web page for display with search results requested by a user. For any of these online applications, Boolean expressions of features may need to be evaluated given an input assignment of features.